(a) Technical Field
The present disclosure of invention relates to a thin film transistor array panel and a manufacturing method thereof.
(b) Description of Related Technology
Liquid crystal displays are now widely used as a type of thin panel display (e.g., flat panel or curved panel). A typical liquid crystal display (LCD) has two spaced apart panels on which electric field generating electrodes are disposed, such as pixel electrodes on one panel and a common electrode disposed on the other. A liquid crystal material layer is interposed between the panels. The liquid crystal display is driven to apply voltages across the field generating electrodes so as to generate corresponding electric fields which extend into or through the liquid crystal layer. These then determine the alignment of liquid crystal molecules of the liquid crystal layer and thus a polarization effect applied to passing through light, thereby forming an image for display to a user who perceives the field modulated light.
Among the different kinds of liquid crystal displays, there is one class where the opposed field generating electrodes that generate the electric field of the liquid crystal layer are formed on a same thin film transistor array panel.
When the two field generating electrodes are formed on the thin film transistor array panel, a relatively large number of insulating layers are typically disposed between the thin film transistor and the field generating electrodes. When contact holes are formed for electrically connecting the thin film transistors to respective ones of the field generating electrodes, the contact hole typically extends through the relatively large number of insulating layers, and as a consequence the width of the contact holes become larger due to the process of etching through so many insulating layers and in particular, due to etching through a plurality of relatively hard insulating layers.
When the widths of the contact holes becomes enlarged in this way, they take away from the finite surface area allotted to each pixel unit and an aperture ratio of the liquid crystal display that uses the thin film transistor array panel is thereby deteriorated.
Meanwhile, when forming a drain contact hole in a region where a gate wire and a drain electrode are both present, in the case of etching through the gate insulating layer and through the passivation layer together, when the formed drain contact hole partially overlaps the gate wire of a corresponding thin film transistor (TFT), a short of the drain electrode and the gate wire may be generated, thereby causing a circuit defect.
It is to be understood that this background of the technology section is intended to provide useful background for understanding the here disclosed technology and as such, the technology background section may include ideas, concepts or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to corresponding invention dates of subject matter disclosed herein.